JPH1145016A - Fixing device of belt system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the operation of fitting parts and to make the device compact by preventing damage to a fixing belt and, at the same time, educing the number of the parts. SOLUTION: The fixing belt 5 is wrapped around a fixing roller 3 and a heat roller 4, a pressure roller 7 for pressing the fixing roller 3 via the fixing belt 5 is provided below the fixing roller 3. On the other hand, in an empty space made by wrapping the fixing belt 5, one holder 22 is disposed. The holder 22 holds two temperature control sensors 17 and 18 for the fixing roller 3 and heat roller 4, respectively, and a discharger 20 for discharging the fixing belt 5, and the temperature control sensors 17 and 18 are brought into contact with the rollers 3 and 4, respectively, and the discharger 20 is brought into contact with the inner surface of the fixing belt 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt-type fixing device provided in an image forming apparatus such as an electrostatographic copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art Before fixing a toner image by a nip, one of the fixing devices preheats the toner image and a recording sheet so that the temperature of a nip portion can be set to be low. There is a device.

More specifically, as shown in FIG. 2, this belt-type fixing device winds an endless fixing belt 5 around a fixing roller 3 and a heating roller 4, and
A pressure roller 7 that presses the fixing roller 3 via the fixing belt 5 is provided below the fixing roller 3, and the recording paper a after the transfer of the toner image is a nip portion between the pressure roller 7 and the fixing belt 5. The guide member 8 for guiding the sheet N to the lower side of the fixing belt 5 is disposed so as to face the lower side of the fixing belt 5.
The toner image and the recording paper a are preheated.

A heating roller 4 is provided in the belt-type fixing device.
And a temperature control means 16 for the heater 15 of the fixing belt 3.
a, a fixing belt portion 5 wound around the heating roller 4
b is detected individually by two temperature detecting sensors 17 and 18 such as a thermistor, and the temperature of the fixing belt 5 in the nip N is maintained at a predetermined fixing temperature in the fixing mode. Based on the temperature detection information from the temperature detection sensor 17 on the fixing roller 3 side, the control unit 19 controls the heater 15 to be turned on and off. Is controlled based on the temperature detection information from the temperature detection sensor 18 on the heating roller 4 side.
9 is configured to control the heater 15 on and off.

On the other hand, the above-mentioned fixing belt 5 is charged by the rotation and further by the contact with the roller means 6 for applying a release agent such as silicone oil and the like. Since the electrification of the fixing belt 5 leads to a fixing failure, for example, a static eliminator 20 such as a static elimination brush is provided.

Conventionally, as shown in the figure, the temperature detecting sensors 17 and 18 are arranged so as to contact the fixing belt portions 5a and 5b wound around the fixing roller 3 and the heating roller 4, respectively. Temperature detection sensor 1
The upper case 2 encloses 7, 18 and the roller means 6 for applying the release agent.

[0007]

However, in such a configuration, the case 2 for covering the sensor and the like becomes large, and the temperature detecting sensors 17 and 18 are connected to the fixing belt portion 5.
Since the fixing belt 5 is in contact with the fixing belt 5a and 5b, there is a problem that the fixing belt 5 is easily damaged.

Further, two sensor holders 22, 22 are required to individually hold the temperature detecting sensors 17, 18 located at locations separated from each other, and the cost is reduced due to the large number of parts. In addition to the high cost, there is a problem in that the assembling work becomes congested.

The present invention takes into consideration the arrangement of sensors so as not to damage the fixing belt, and at the same time, reduces the number of parts to achieve easy assembly work and downsizing of the apparatus. It is an object.

[0010]

That is, according to the present invention, an endless fixing belt is wound around a fixing roller and a heating roller, and a pressing roller which presses the fixing roller via the fixing belt is provided as a fixing roller. In the belt-type fixing device provided on the lower side, one holding member is disposed in a space around the fixing belt, and the holding member includes two temperature detection sensors for a fixing roller and a heating roller; Holding a static eliminator for static elimination for the fixing belt,
It is characterized in that the temperature detection sensor is configured to contact the roller and the static eliminator is configured to contact the fixing belt.

[0011] According to the above configuration, the temperature detection sensor and the static eliminator are disposed in the space where the fixing belt is wound, and the upper case can be made compact. In addition, since the temperature detection sensor is in contact with the roller, the fixing belt is not damaged.

In addition, since the two temperature detection sensors and the static eliminator are combined, it is possible to easily attach these three components to one holder, thereby reducing the number of components. Simultaneous assembly work is achieved at the same time as cost reduction.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a belt-type fixing device of an electrostatographic copying machine (an example of an image forming apparatus), and a lower case 1.
A fixing roller 3 and a heating roller 4 are provided on an upper case 2 which is configured to be openable and closable with respect to the endless fixing belt 5.
Roller means 6 for applying a release agent such as silicon to the belt surface is provided.

The lower case 2 includes a pressing roller 7 for pressing the fixing roller 3 from below via the fixing belt 5, and the recording paper a after transferring the toner image to the pressing roller 7 and the fixing belt 5.
And a guide member 8 for guiding the nip portion N between the guide member 8 and the lower side of the fixing belt 5. Forming path A and recording paper a after toner image transfer
Preheats the toner image and the recording paper a while passing through the heating roller 4 and the lower side of the winding of the fixing belt 5.

As described above, by preheating the toner image and the recording paper a, it is possible to set the fixing temperature at the nip N low, and since the heat capacity of the fixing belt 5 is small. At the time of fixing at the nip portion N, heat is quickly taken away by the toner and the recording paper a,
When the temperature of the fixing belt 5 is lowered, the molten toner is not heated more than necessary, so that the recording paper a
Is reliably separated from the fixing belt 5, so-called offset is prevented.

The fixing belt 5 has a release layer made of silicon rubber or the like provided on an outer surface of an endless belt made of metal such as metal nickel or an outer surface of an endless belt made of resin such as polyimide resin. The fixing roller 3 and the pressure roller 7 are formed by providing coating layers 11 and 12 made of a heat-resistant elastic material such as silicon rubber on roller cores 9 and 10 made of metal such as aluminum. The hardness of the elastic coating layer 11 on the third side is set equal to or softer than the hardness of the elastic coating layer 12 on the pressure roller 7 side.

The heating roller 4 is made of, for example, a metal roller cylinder 13 made of aluminum or the like, and a coating layer 1 made of Teflon or the like.
4 and a heater 15 built in the roller cylinder 13. A heater is also provided in the fixing roller 3 or the pressure roller 7 as necessary. In this embodiment, the heater 15 is used. The heat energy of the heated roller 4 is transmitted to the fixing roller 3 by using the fixing belt 5 as a heat transfer medium, and the temperature of the heating roller 4 under the fixing mode and the stable standby mode of the fixing device. For management, a temperature control means 16 for the heater 15 of the heating roller 4 is provided.

The temperature control means 16 detects the surface temperatures of the fixing roller 3 and the heating roller 4, for example, temperature detection sensors 17 and 18 such as thermistors, and the temperature detection information from the temperature detection sensors 17 and 18. Heater 15
And a control unit 19 for turning on and off the power supply. In the fixing mode, the temperature of the fixing belt 5 at the nip portion N is maintained at a predetermined fixing temperature (for example, 170 ° C.) by the temperature detection sensor 17 on the fixing roller 3 side. The on / off control of the heater 15 of the heating roller 4 is performed based on the temperature detection information.

On the other hand, in the stable standby mode, when the fixing is restarted, the temperature of the fixing belt 5 at the nip portion N is set to a predetermined fixing temperature within a short time, that is, the temperature of the heating roller 4 is reduced. A temperature higher than the fixing temperature (for example, 175
(° C.), the heater 15 of the heating roller 4 is turned on and off by the temperature detection sensor 18 on the heating roller 4 side.

In the belt-type fixing device having the above configuration, the two temperature detecting sensors 17 and 18 and the fixing belt 5 are used.
And a static eliminator (for example, a static elimination brush) 20 for removing the static electricity is attached to one holder 22 via the holding members 21, and the holder 22 is disposed in the space where the fixing belt 5 is wound. The temperature detection sensor 17 is brought into contact with the fixing roller 3, the other temperature detection sensor 18 is brought into contact with the heating roller 4, and the static eliminator 20 is brought into contact with the inner surface of the fixing belt 5.

According to the above configuration, by disposing the temperature detection sensors 17 and 18 in the space where the fixing belt 5 is wound, the upper case 2 is compactly formed so as to be depressed in the sensor arrangement area up to that point. Can be formed.

Further, since the temperature detecting sensors 17 and 18 are in contact with the rollers 3 and 4, the fixing belt 5 is not damaged at all. The temperature detection sensors 17 and 18 and the static eliminator 20 are combined, so that it is possible to easily attach these three parts to one holder 22, thereby reducing the number of parts and reducing cost. At the same time, the assembling work is facilitated.

[0023]

As described above, the present invention effectively utilizes the space around the fixing belt, which is a play space,
The unique technology of arranging sensors in this wrapping space allows the number of parts to be reduced, the associated assembly work to be simplified, and the device to be more compact. The belt no longer receives any damage from sensor contact.

[Brief description of the drawings]

FIG. 1 is a sectional view of a belt-type fixing device according to the present invention.

FIG. 2 is a sectional view of a conventional belt-type fixing device.

[Explanation of symbols]

3 fixing roller, 4 heating roller, 5 fixing belt, 7
... pressure roller, 17, 18 ... temperature detection sensor, 20 ...
Static eliminator, 22 ... Holder.

Claims (1)

[Claims] 1. A fixing roller and a heating roller,
A belt-type fixing device in which an endless fixing belt is wound around and a pressure roller that presses the fixing roller via the fixing belt is provided below the fixing roller.
Place one holder in the space around the fixing belt,
The holder has a fixing roller and a heating roller.
A belt-type fixing device comprising: a plurality of temperature detection sensors; and a static eliminator for static elimination of the fixing belt, and the temperature detection sensor is in contact with a roller and the static eliminator is in contact with the fixing belt.